1. Field of Invention
This invention relates to technical fabrics, and more specifically to technical fabrics comprising webs bonded to barrier layers.
2. Description of Related Art
In the development of performance fabrics for outwear and other garments, it is common practice to combine conventional fabrics with functional barrier layers with the goal of obtaining a performance fabric that possesses the beneficial characteristics of each. See, e.g., U.S. Patent App. Publication No. 20090186548 to Rock et al. (MMI-IPCO, LLC). However, providing a performance fabric that optimally balances good aesthetic characteristics, durability, breathability and waterproofness has remained an elusive goal.
The attachment of a waterproof and breathable barrier layer, whether a film or coating, to a fabric is commonly accomplished through the use of an adhesive, or basecoat layer. Unfortunately however, adhesive layers can in their attempt to provide good waterproofness and durability, also provide the resulting fabric laminate with undesirable aesthetic characteristics and significantly reduced moisture vapor transmission. A number of potential solutions to this problem have been proposed. In general, attempts to address this problem can be categorized as a continuous adhesive layer approach or a discontinuous adhesive layer approach.
In the continuous adhesive layer approach, the adhesive of the adhesive layer must itself allow for transmission of water vapor within its matrix. Exemplary adhesives include hydrophilic polymers, open cell polymer foams and microporous polymers. The continuous adhesive layer approach allows for essentially total contact between adhered layers and as a result, offers potentially high waterproofness values. However, hydrophilic polymer adhesives swell and shrink in response to intermittent exposure to liquid water, compromising durability to laundering; typically breathe less than air porous layers; and typically impart a firmness of hand to the composite fabric. Open cell polymer foam adhesives can offer softness of hand and improved breathability, but due to their expanded structure represent relatively weak layers. Finally, microporous polymer adhesives typically lack softness of hand, and are additionally subject to loss of breathability in use through pore contamination.
In the discontinuous adhesive layer approach, the adhesive is applied discontinuously between adjacent layers, such that water vapor can pass through portions of the fabric free of adhesive. Typically, the adhesive is applied in a dot, grid, or random pattern. The discontinuous adhesive layer approach is more desirable than the continuous adhesive layer approach from a hand, drape, and vapor permeability standpoint. However, fabric laminates prepared by the discontinuous adhesive layer approach can suffer from less than optimal waterproofness values (due to this reduced coverage) and/or surface distortion after repeated laundering cycles, and sometimes undesirable show-through of the underlying adhesive pattern especially after laundering if particularly sheer fabrics are employed.
These problems have inspired a variety of attempts to provide improved methods of manufacturing adhesive laminates, including the following.
U.S. Pat. No. 5,660,918 to Dutta (W.L. Gore) purports to address some of these problems through the use of a discontinuous but interconnected pattern of adhesive between a hydrophilic polymer layer and a fabric layer.
U.S. Pat. No. 5,750,444 to Jarrett et al. (Nordson Corp.) discloses a breathable laminated fabric having two layers of porous non-woven textile materials and intermediate, fluid pervious hot melt adhesive, disposed between contact areas of said textile layers, and comprising a fine, fibrous random adhesive matrix.
U.S. Pat. No. 6,190,482 to Colasanto (Enterprise Coatings) discloses a method of laminating multiple layers of textile and/or polymer materials together comprising generating a discontinuous layer of adhesive with a precise pattern of voids by means of temporarily introducing sets of parallel yarns or, alternatively, mesh-like webs in contact with an initially uniform layer of adhesive temporarily carried on a release-coated carrier. After the adhesive layer and the mesh-like web have been pushed into contact with a first fabric layer, the release-coated carrier is stripped away, along with the mesh-like web, from the first fabric layer. The adhesive layer remaining on the first fabric layer will exhibit a discontinuous pattern that is complementary to the mesh-like web pattern. Subsequently, a second fabric, or film, is bonded to the exposed adhesive surface on the first fabric to create a laminated material exhibiting air permeability or moisture permeability.
U.S. Pat. No. 7,329,622 to Ulli (Solipat AG) discloses a method and a device for depositing partial surface coatings on both sides of a film so that the film may be laminated on both sides.
U.S. Patent App. Publication No. 20080223500 (Colasanto et al. for Dartex Coatings) discloses a method of forming an air-permeable composite fabric, said method comprising the steps of: (a) providing a first fabric layer; (b) providing a second fabric layer; (c) providing an adhesive layer comprising a polyurethane between the first fabric layer and the second fabric layer; and (d) calendering together the first fabric layer, the second fabric layer and the adhesive layer to provide the air-permeable composite fabric, wherein a temperature, a pressure and a duration of the calendering step are selected to provide the fabric with a predetermined air permeability.
Despite the foregoing developments, there is still room in the art for further improved methods for providing fabric laminates with good aesthetic characteristics, durability, moisture vapor transmission and hydrostatic resistance.
All references cited herein are incorporated herein by reference in their entireties.